1. Technical Field
The presently disclosed subject matter relates to a semiconductor light emitting device, and in particular, to a semiconductor light emitting device that can serve as a light source for emitting light to be introduced into a light guide plate of a backlight system for a liquid crystal display or the like. The presently disclosed subject matter also relates to a method for manufacturing the semiconductor light emitting device.
2. Description of the Related Art
Conventional backlight systems (for use in a liquid crystal display device, a translucent non-illumination display element for characters and figures, and the like) are mainly composed of a light guide plate and a light source for emitting light to be introduced into the light guide plate. Examples of such a light source include a fluorescent lamp (in particular, a cold cathode fluorescent lamp), a semiconductor light emitting device (in particular, an LED), and the like. Of these, LEDs are small in size, light in weight, and easy to be driven with a simple driving circuit and method. Many portable devices having a small-sized liquid crystal display device employ such LEDs as a light source for the backlight system.
A common backlight system can include a mounting board 50, and a light guide plate 51 and an LED 52 which are disposed on the mounting substrate 50, as shown in FIG. 1. In this configuration, the LED 52 has an optical axis X that is substantially perpendicular to the light incident surface 53 of the light guide plate 51 and substantially parallel with the surface of the mounting board 50. In other words, the LED 52 is of a side-view type.
The LED 52 of this type can include a device substrate 54, an LED element 55 mounted on the substrate 54, and a sealing body 56 made of a resin for sealing these components. The sealing body 56 can have a surface on the mounting board 50 side and an outer surface on the opposite side to the mounting board 50. Light-shielding reflective members 57a and 57b are provided to these surfaces of the sealing body 56.
The LED 52 can emit light which may be directed to the pair of the light-shielding reflective members 57a and 57b of the sealing body 56. The incident light is reflected by the light-shielding reflective members 57a and 57b to be converged within the thickness range of the light guide plate 51, and then is incident on the light incident surface 53 of the light guide plate 51 to enter the light guide plate 51. The sealing body 56 can have a surface 58a which is substantially perpendicular to the optical axis X and a pair of surfaces 58b and 58c to which no light-shielding reflective member is provided and which are substantially parallel with the optical axis X. The LED 52 can emit light which is directed to these surfaces 58a, 58b, and 58c to be diffused in the width direction of the light guide plate 51. Then, the diffused light is incident on the light guide plate 51 from the light incident surface 53 thereof.
This configuration can allow the light emitted from the LED 52 to effectively enter the entire incident surface 53 of the light guide plate 51 so that the light can be spread over the light guide plate 51 in the parallel direction with the surface thereof. This can achieve a uniform and bright backlight system. (See, for example, Japanese Patent Application Laid-Open No. 2004-127604.)